Where, 'O' Where Shall I Put You?

On-air challenge: Every answer is a two-word phrase in which the letter "O" is added at the end of the first word to make the second word. For example, given the clue "pack animal owned by Thomas Jefferson's first vice president," the answer would be "Burr burro."

Last week's challenge: Draw a regular hexagon and connect every pair of vertices except one. The pair you don't connect are not on opposite sides of the hexagon but along a shorter diagonal. How many triangles of any size are in this figure?

Answer: 82 triangles

Winner: John Wilson of Shoreview, Minn.

Next week's challenge: What specific and very unusual property do these five words have in common: school, half, cupboard, Wednesday and friend? Identify the property and name a sixth word that shares the property. Any word having this property will be counted correct.

If you know the answer to next week's challenge, submit it here. Listeners who submit correct answers win a chance to play the on-air puzzle. Important: Include a phone number where we can reach you Thursday at 3 p.m. ET.

Copyright 2013 NPR. To see more, visit http://www.npr.org/.

Transcript

RACHEL MARTIN, HOST:

This is WEEKEND EDITION from NPR News. I'm Rachel Martin. Make sure your coffee cup is full because it is time for the puzzle.

(SOUNDBITE OF MUSIC)

MARTIN: And joining me now is WEEKEND EDITION's puzzle-master Will Shortz. Good morning, Will.

WILL SHORTZ, BYLINE: Good morning, Rachel.

MARTIN: So, Will, you're now back from the World Puzzle Championship, which took place in Croatia. How'd it go?

SHORTZ: Well, it was great. A German solver won. He is just like a machine, so good at solving puzzles - Ulrich Voigt. Americans finished second and third - Thomas Snyder and Palmer Mebane. And in the team competition, the U.S. finished third behind Germany and Japan.

MARTIN: Great. Well, you had us drawing hexagons and counting triangles last week - a little geometry. Remind us, Will, what was last week's challenge.

SHORTZ: Yes. The challenge was to draw a regular hexagon and connect every pair of vertices, except one - not the pair that are opposite a hexagon but along a shorter diagonal. And the question was how many triangles of any size are in the figure? Well, we got a lot of answers but the correct answer is 82. And you can get that by - if you draw that extra line that I said to take out, there are 110 triangles. And there are exactly 28 triangles that use that line that's removed. And so the result is 82.

MARTIN: OK. Well, about 65 out of more than 300 of our listeners counted 82 triangles. And our randomly selected winner this week is John Wilson of Shoreview, Minnesota. He joins us on the line. Congratulations, John.

JOHN WILSON: Thank you very much, Rachel.

MARTIN: So, those were a lot of triangles to count. I mean, did you figure this out on your own or did you have help from someone who's good at geometry?

WILSON: Yeah, you know, I had huge help. My daughter in second grade, Anna, is diving into all sorts of math challenges. And just the other week she got to count triangles in a shape too.

MARTIN: Go, Anna.

WILSON: Yeah, exactly. Anna got to check my work for a change and...

MARTIN: Nice.

WILSON: ...tried to stump me by finding a triangle I had missed. So is a fun way to turn the tables when it came to homework.

MARTIN: I love it. I know your children aren't here to help you right now, but are you ready to play the puzzle?

WILSON: I know. I'll try to muddle through. Just like the politicians get ready with their debate camp, I really needed a puzzle camp, but I'll just drink a coffee and hope for the best.

MARTIN: OK. I believe in you, John. I think you can do this. Will, let's do it.

SHORTZ: All right, John. Hey, I recognize your name from the American Crossword Puzzle tournament as a contestant, so I have high expectations here.

MARTIN: He's done this before.

WILSON: Uh-oh.

SHORTZ: Uh-oh. So, every answer today is a two-word phrase in which the letter O is added at the end of the first word to make the second word. You answer the clues. For example, if I said a pack animal owned by Jefferson's first vice president, you would say Burr burro.

MARTIN: OK. You got it, John?

WILSON: OK.

MARTIN: All right. Let's go.

SHORTZ: Number one: a teaser for an annual school dance.

WILSON: It's a prom promo.

SHORTZ: That's it. Number two: leave Ecuador's capital.

WILSON: Quit Quito.

SHORTZ: Sound output of a German car.

WILSON: Audi audio.

SHORTZ: That's it. Gambling game promoted by a rival of Google.

WILSON: Let's see, a rival of Google - Yahoo or...

SHORTZ: And think of as a search engine.

WILSON: Oh, Bing bingo.

MARTIN: Nice.

SHORTZ: That's it. Greeting from Satan.

WILSON: Oh, a hell hello.

SHORTZ: That's it. A stylish Marx brother.

WILSON: A chic Chico.

SHORTZ: That's it. An old classroom handout about a silent performer.

WILSON: A mime mimeo.

SHORTZ: Uh-huh. A two-for-one deal on several items of personal grooming.

WILSON: Coupon, sale - Rachel, can you jump in?

MARTIN: Oh, man.

SHORTZ: And for those items of personal grooming, what do you put in your hair?

MARTIN: Exactly. For playing our puzzle today, you'll get a WEEKEND EDITION lapel pin, as well as puzzle books and games. You can read all about it at npr.org/puzzle. And, John, before we let you go, what Public Radio station do you listen to?

WILSON: It's a great station to know. It's KNOW, 91.1 in St. Paul.

MARTIN: All right, great. John Wilson of Shoreview, Minnesota, thanks so much for playing the puzzle this week, John.

WILSON: Thank you very much.

MARTIN: OK, Will, what have you cooked up for us next week?

SHORTZ: Yes, you know, at the World Puzzle Championship last week, we were sitting around the table and several of us were giving puzzles to each other. And here's one I thought of on the spot: What specific and very unusual property do the following five words have in common: school, half - that's H-A-L-F, cupboard, Wednesday and friend? So what specific and very unusual property do these five words have in common: school, half, cupboard, Wednesday, friend?

And if you have the answer, name a sixth word that shares the same property. And any word that has this property will be counted correct.

MARTIN: OK, when you have the answer, go to our website, npr.org/puzzle and click on the Submit Your Answer link - just one entry per person, please. The deadline for entries is Thursday, October 18th at 3 P.M. Eastern Time. Please include a phone number where we can reach you at about that time.

And if you're the winner we'll give you a call, and you will get to play on the air with the puzzle editor of The New York Times and WEEKEND EDITION's puzzle-master, Will Shortz.